The invention relates to a belt guiding mechanism suitable for guiding a belt extending through the belt guiding mechanism and locking said belt against movement, which belt guiding mechanism comprises a cam that is capable of movement relative to a bearing surface, said belt being movable in a tensioning direction and in the opposite direction through a passage present between said cam and said bearing surface, which cam is movable in a direction towards the bearing surface for locking the belt against movement.
The invention also relates to a child vehicle seat provided with such a belt guiding mechanism.
With such a belt guiding mechanism as known from European patent EP-B1-0 173 726, which is used in a vehicle, the belt is movable in the tensioning direction for tensioning the belt firmly against a person seated in the vehicle. The belt is movable in the opposite direction of the tensioning direction so as to allow slight forward movement of said person.
If said forward movement is caused by the vehicle suddenly decelerating or colliding, relatively large forces are exerted on the person and consequently by the person on the belt, as a result of which the cam is moved in a direction towards the bearing surface. This causes the belt to be clamped down between the cam and the bearing surface, so that the belt is locked against movement in the opposite direction of the tensioning direction.
In case of such a collision, one end of the belt is furthermore locked against movement in the opposite direction of the tensioning direction in an automatic belt retractor.
A drawback of the known belt guiding mechanism is the fact that said locking of the belt is effected both as a result of the operation of the automatic belt retractor and as a result of the belt being locked against movement between the cam and the bearing surface. The belt that moves through the belt guiding mechanism is relatively smooth so that the belt can readily be rolled up in the automatic belt retractor. A drawback of such a relatively smooth belt is that the belt will fairly easily slide off the shoulder of a person seated in the vehicle, for example. In case of a collision, a person's shoulder will first move relative to the belt before the belt is moved in the opposite direction of the tensioning direction and locking of the belt can take place.